1. Field of the Invention
The present invention relates to a device housing a battery (batteries) such as a battery pack or mobile telephone, and to a charging pad that transmits power by magnetic induction to the device housing a battery to charge the battery inside.
2. Description of the Related Art
A charging pad (charging stand, charging cradle) has been developed to charge a battery housed in a device by transmitting power from a power supply coil (primary coil) to an induction coil (secondary coil) by magnetic induction. (Refer to Japanese Laid-Open Patent Publication HEI 9-63655 (1997) and Utility Model Registration No. 3011829.)
JP H09-63655 A cites a configuration with a charging pad housing a power supply coil driven by an alternating current (AC) power source, and a battery pack housing an induction coil that magnetically couples with the power supply coil. The battery pack houses circuitry to rectify the AC power induced in the induction coil and supply the rectified power to charge the battery. With this system, a battery pack can be placed on the charging pad to charge the battery pack battery without direct physical contact.
JP 3011829 U cites a configuration with a battery housed in the bottom part of an electrical device, a secondary-side charging adapter provided beneath the battery, and an induction coil and charging circuit housed in the secondary-side charging adapter.
A charging pad is also cited that is provided with a power supply coil to magnetically couple with the induction coil. The device housing a battery is placed on the charging pad to magnetically couple the secondary-side charging adapter, power is transmitted from the power supply coil to the induction coil, and the battery in the device is charged.